Could not sign in. Please check your network connection and try again

Hi. I have been getting the error "Could not sign in. Please check your network connection and try again." For imessage and facetime on my ipad 4 16gb wifi only. This only started when I upgraded to ios7. i have tried resetting all and my network settings, changing the DNS to 8.8.8.8 and 8.8.8.8.4.4.4.4, setting my time and date to automatic, and changing my apple id password. I tried to use another person's apple id to sign in but I'm getting the same error. I'm pretty sure my network connection is not the problem because my parents are both using iphones and have upgraded to ios7 but imsg and facetime still works for them. Help?